Fiber fractionating apparatus and process



Oct. 31, 1967 J. J. LAFRANCA, JR, ETAL 3,349,902

FIBER FRACTIONAT AAAAAAAAAAAAAAAAAAAA SS Filed Oct. 22, 1965 5 Sheets-Sheet l Oct. 31, 1967 J. J. LAFRANCA, JR, ETAL 3,

FIBER FHACTIONATING APPARATUS AND PROCESS Filed Oct. 22, 1965 5 Sheets-Sheet 2 INVENTORS JOSEPH J. LAFRANCA,JR. MAYER MAYER,JR. HEBER w. WELLER,JR.

BY K AAWA ATTORNEY Oct. 31, 1967 J. J. LAFRANCA, JR., ETAL 3,349,902

FIBER FRACTIONATING APPARATUS AND PROCESS Filed Oct. 22, 1965 5 Sheets-Sheet 3 M OK ATTORNEY 31, 1967 J. J. LAFRANCA, JR. ETAL 3,349,902

FIBER FRACTIONATING APPARATUS AND PROCESS Filed Oct. 22, 1965 5 Sheets-Sheet 4 INVENT 015 JOSEPH J. LAFRAN MAYER MAYE CA,JR. mm. HEBER w. WELLER,JR.

ATTORNEY Oct. 31, 1967 J. J. LAFRANCA, JR. ETAL 3,349,902

FIBER FRACTIONATING APPARATUS AND PROCESS 5 Sheets-Sheet 5 Filed Oct. 22, 1965 FIGS ATTORNEY United States Patent 3,349,902 FIBER FRACTIONATING APPARATUS AND PROCESS Joseph J. Lafranca, Jr., Metairie, Mayer Mayer, Jr., New

Orleans, and Heber W. Weller, Jr., Metaine, La., assignors to the United States of America as represented by the Secretary of Agriculture Filed Oct. 22, 1965, Ser. No. 502,727 9 Claims. (Cl. 209--2) A nonexclusive, irrevocable, royalty-free license in the invention herein described, for all Government purposes, throughout the world, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to an apparatus for fractionating fibers into length-groups.

More specifically, it deals with an apparatus for electrostatically aligning fibers and removing the short fibers from cotton lint. Another object of our invention is to provide a novel process for removing short fibers from textile fibers.

As used herein, the term fibers relates to the individual components of cellulosic or noncellulosic staple textile materials such as cotton, regenerated cellulose, polyester, polyamide, polyvinyl, the natural nitrogen-containing fibers, and the like. Because of its wide use, cotton w1ll frequently be referred to below as the fiber, but it is to be understood that this usage is illustrative only.

The term fabric relates to woven or nonwoven mateials. I The term lint as used herein, relates to a collection of fibers of various lengths.

The term short fibers relates to the shorter portions of the lint, usually fibers or portions of fibers not longer than about three-eighths inch. I

The presence of short fibers has several disadvantages in the processing of lint cotton into yarn and/or fabric. In the first place, short fibers reduce the strength of the yarn. This results in a greater number of ends down or breakage during the spinning process, thereby decreasing the eificiency of the process and increasing the cost. In the second place, these short fibers increase the total number of ends per unit length of the resulting yarn. These ends tend to protrude and impart a fuzzy character detrimental to the quality of the yarn. In the third place, when these fuzzy yarns are dyed, the fiber ends do not take the same color but do reflect light. Consequently,

the fabric or yarn does not acquire as strong a shade as the amount of dye used should produce. This results in additional expense to the dyer. In the fourth place, yarns and fabrics produced without these short fibers are characterized by their increased strength, their evenness, their smoothness, their uniformity, and their commercial desirability.

In the copending application of Mayer Mayer, Jr., and Heber W. Weller, Jr, Ser. No. 374,864, filed June 12, 1964, there is described and claimed another type of apparatus for electrostatically removing short fibers from cotton lint. That apparatus comprises means for generating an electrostatic field defined by an outer stationary incu rvate conductive electrode and a rotating, inner cylindrical electrode between which fibers are fed. The fibers are then rotatably conveyed in the direction of decreasing electrode spacing to a doffing means spaced from the rotating cylinder a predetermined distance necessary for removing fibers of a length longer than said distance. While the apparatus of Ser. No. 374,864 serves a most useful purpose in the fractionation of fibers into length groups in small quantities and is excellent for laboratory use, it has the disadvantage of low productive capacity which is of particu- 3,349,902 Patented Oct. 31, 1967 lar significance in the textile field where large quantities of fibers are to be processed.

In the copending application of Mayer Mayer, Jr., Heber Weller, Jr., and Joseph J. Lafranca, Jr., Ser. No. 374,- 863, filed June 12, 1964, there is described and claimed another type of apparatus and process for electrostatically removing short fibers from cotton lint. The latter apparatus comprises means for generating an electrostatic field, having a nonuniform potential gradient, between two stationary electrodes and an endless belt moving continously between the two stationary electrodes in a direction transverse to the nonuniform electrostatic field, so that the region'between one edge of the moving belt and the stationary electrodes has a higher potential gradient than the region between the opposite edge of the belt and the electrodes. When fibers are fed into the electrostatic field on the side having the lower potential gradient they are aligned according to fiber length between the side having the lower potential gradient and the side having the higher potential gradient. Surprisingly, the longer fibers moved to the area of the highest potential gradient. With a suction mechanism at the outgoing end of the endless belt, the fibers can be fractionated into various length groups. The apparatus of Ser. No. 374,863 also is excellent for laboratory work but has the disadvantage of low productive capacity and the diificulty of being scaled up for commercial production.

In the apparatus which is the subject of the present invention, an electrostatic field is produced by rotating, parallel, cylindrical electrodes capable of fractionating masses of fibers at an unexpectedly rapid rate.

The present apparatus comprises any suitable means for introducing loose masses of relatively untangled, individualized fibers into an electrostatic field having both uniform and nonuniform potential gradients produced by specially shaped and positioned electrodes. This electrostatic field causes the longer fibers to align themselves parallel with the lines of force and to migrate in this position (i.e., at right angles to the electrodes) toward the stronger regions within the field while the short fibers remain relatively unaifected. Consequently, the longer fibers may be readily separated from the shorter ones.

Some care needs to be given to the method of feeding the fibers into the electrostatic field. Best results are obtained when they are delivered gently into the opening of the apparatus, as described in detail below. The usual method for delivering fibers is with positive pressure air. Should this air stream be too strong, the aerodynamic force will interfere with the electrical force and will reduce the effectiveness of the electrostatic field.

The electrostatic field is produced by four, or more, parallel, rotating cylindrical elements symmetrically arranged in two equal groups of elements on each side of an imaginary centerline, The following description of the preferred apparatus will involve six elements, three on each side of the imaginary centerline. However, as will readily be apparent to those skilled in the art, when the apparatus has four rotating cylindrical elements, there will be two such elements on each side of the imaginary centerline. For simplicity, the function of the three elements on one side of the imaginary centerline will be discussed. It will be understood, however, that the elements on the opposite side of the imaginary centerline are located and function as a mirror-image of the side being described.

Two of the parallel cylindrical elements are maintained at the same electrostatic potential, and counter-rotate in close proximity to form one electrode. The third rotating cylindrical element, having an axis of rotation parallel to the first two, is maintained at a different electrostatic potential from the potential of the first two and forms the opposing electrode, thus setting up the electrostatic field of force. This third cylindrical, rotating element is situated at a finite distance from the closer of the first two cylindrical elements. The patricular finite distance depends upon the potential employed and it is a critical feature of our invention that the finite distance is sufficient to prevent arcing across the electrodes. Potentials ranging from about 0.5 to 30 kilovolts per inch of finite distance may be used. When a potential of 60 kilovolts is employed, a finite distance of about 2.25 inches is a good practice.

These opposing electrodes enclose one-half of a region, the other half of the region also containing three electrodes whose function is similar to the first three. It is the latter three that form the mirror-image mentioned above. Each combination of the three cylinders forms a strong electrostatic field. However, it is the total field produced by the cylindrical electrodes and the apparatus associated with it that is the subject of this invention.

Although not a specific requirement, best results are obtained when the first pair of counter-rotating cylinders have different diameters, the larger of the pair being closer to the third rotating cylinder, and the smaller of the pair being closest to the opening where the fibers enter. However, it is a critical feature of the apparatus of this invention that the pair of cylindrical elements be properly spaced and electrically connected so that they function as a single electrode. We also prefer that the surface of this closer element rotates in the direction from lowest to highest field intensity. Likewise, we prefer to have the rotation of the third element such that the surface rotates in the direction from highest to lowest field intensity. In other words, these two cylinders rotate in the same direction. The reasons for this will be described more fully below.

One, but not the only embodiment of an apparatus suitable for the practice of our invention is described in the accompanying drawings in which:

FIGURE 1 is a pictorial view showing the mechanical feature of the preferred embodiment of our invention.

FIGURE 2 is a sectional view showing the essential features of the preferred embodiment of the invention, in which two groups of three elements each are disposed on each side of the imaginary centerline referred to above. This centerline is indicated by the broken line A-B on FIGURE 2.

FIGURE 3 is a sectional view of an embodiment of the invention in which two electrodes are on each side of the imaginary centerline.

FIGURE 4 is an embodiment of the invention in which only half of the apparatus of FIGURE 1 is used, one of the mirror images being dispensed with and replaced by a nonconductive wall.

FIGURE 5 is an embodiment, similar to that of FIG- URE 4, except that one half of the apparatus of FIGURE 3, is replaced by a nonconductive wall.

Referring to FIGURE 2, the loose masses of relatively untangled and disoriented fibers are fed through the entrance chamber 11 into the region between rotating, cylindrical element 12 and its mirror image, 112. Although not so limited, we prefer to have cylindrical elements 13 and 113 contiguous with and electrically connected to elements 12 and 112, respectively, by electrical connectors 14 and 114. It is an advantage to have elements 12, 112, 13, and 113 electrically grounded as shown through contactor strips 15 and 115 by conductors 16 and 116. Referring to FIGURE 1, elements 12, 112, 13, and 113 are rotatably mounted in bearings 17, 18, 117, 118, 19, 20, 119, and 120, and are driven by pulleys 21, 121, 22, 23, 123, 24, and through belts 26, 126, 27, and 127, and by motors 28, 29, and 129.

Although not so limited, we prefer to have cylindrical elements and 130 rotating as shown in FIGURE 2 and charged through contactor strips 31 and 131 by conductors 32 and 132. As shown in FIGURE 1, elements 30 and 130 are rotatably mounted in bearings 33, 34 (not 4 shown), 133, and 134, insulated from the frame by insulator blocks 35 and 135, and driven by pulleys 36, 136, 137, and 138 through belts 39 and 140 by motor 141.

Long fibers migrating from the region of lowest field intensity between cylindrical elements 12 and 112 to regions of high field intensity between elements 13 and 30 and also between elements 113 and may be removed and collected by any means common to the art. We prefer to use nonconducting fingers 42 and 142 rotatably mounted in insulated bearings 43 and 143 as shown in FIGURE 1, and driven by pulleys 51, 52, 151, and 152 through belts 53 and 153 by motors 54 and 154. Fingers 42 and 142 mechanically sweep the long fibers from within the high-field intensity regions and transfer them into chambers 44 and 144, FIGURE 2, where air currents remove the fibers from the fingers and deposit them on removable screens 45 and 145. These air currents may result from positive or negative pressure air.

Most of the short fibers, which are less readily attracted to the high field-intensity regions, come into contact with rotating elements 12, 112, 30, and 130, and remain on these elements, the rotation of which conveys the short fibers outside the field, as much as 70% of them passing out on the surfaces of elements 30 and 130. This was unexpected. These short fibers may be removed by any mechanical means common to the art such as felt wipers 46, 146, 47, and 147 shown in FIGURE 2. The short fibers removed by felt wipers 46 and 146 may be manually recovered. The short fibers removed by felt wipers 47 and 147 are mechanically recovered in chamber 48. While we prefer to use felt wipers, other means known to the art also may be used, such as suction air.

A certain number of the short fibers are attracted to elements 13 and 113, but they are too short to be removed by the rotating fingers 42 and 142 and also pass out of the high-intensity field on the surfaces of elements 13 and 113 where they may be removed by felt wipers 49 and 149. It is a critical feature of the apparatus of this invention that the fingers 42 and 142 do not pass closer to the elements than the mid-point of the length of the short fibers that are to be separated from the lint.

As noted above, about 70% of the short fibers are recovered in chamber 48. It is a critical feature of chamber 48 that it is conductive and maintained by conductor 50 at the same potential as elements 30 and 130, otherwise felt wipers 47 and 147 will not function properly.

The speed of the surfaces of the cylinders is dependent upon two factors, one physical and the other electrical. If the speed of the surface is sufficiently great to cause the aerodynamic drag on the fibers to adversely affect the electrical forces, less efficient fractionation is obtained. This is the physical factor. During the operation of the apparatus, many long fibers are aligned on elements 30 and 130 but since the long fibers are attracted by the higher potential gradient they travel backwards from the direction of these elements towards the high field intensity. Consequently,'the rate of travel of the surface of elements 30 and 130 should be less than the speed of migration of these long fibers. This is the electrical factor.

It is an advantage of the apparatus of our invention that the cylindrical electrodes are parallel and can be scaled up (lengthened) to give the production desired.

Another advantage that the field is shaped by opposing sets of curved surfaces in such a manner as to produce excellent separation of short fibers from longer lint (textile fibers).

It is still another advantage that the rotation of all the elements in the field enables the short fibers to be removed directly from the field.

As already mentioned above, the apparatus may have only four cylindrical elements, that is, two on each side of the imaginary centerline. This is shown in FIGURE 3. Again, as in FIGURE 2, the centerline is designated by broken line A-B. The embodiments of these two figures are essentially the same, except that in FIGURE 3, cylinders 12, 112, and their associated structures have been omitted.

In still another modification of the preferred embodiment, as shown in FIGURE 4, the imaginary centerline A-B can be replaced by a real, nonconductive boundary, that is by an actual wall 55. When this is done it is possible to eliminate one of the mirror images, thereby reducing the number of operating elements by one-half. Thus where the preferred embodiment of FIGURE 2 (six cylinders) is so modified, the resulting apparatus will be that shown in FIGURE 4. When the four cylinder embodiment (FIGURE 3) is so modified, the apparatus will obviously be as shown in FIGURE 5. When one of the mirror images is eliminated, the parallel, cylindrical rotating elements remaining will fractionate loose masses of relatively untangled, individualized fibers satisfactorily, but at a lower production.

It is also within the scope of our invention to combine the fiber fractionating apparatus with other textile equipment such as a textile carding machine. When this is done, relatively loose masses of individualized fibers from the latter may be fed directly into the apparatus of this invention.

It is also within the scope of this invention to replace the nonconductive' rotating fingers with an endless means for removing the long fibers from the high intensity field conveying them to other textile equipment.

We claim: 1

1. Apparatus for separating short fibers from loose masses of relatively untangled mixtures of individualized long and short textile fibers which comprises:

(a) input means for admitting a loose mass of a relatively untangled mixture of individualized long and short textile fibers into the apparatus;

(b) six parallel, rotatable cylindrical electrode elements symmetrically arranged in two groups of three elements on opposite sides of a center line to form a mirror image of each other,

( 1) said six electrode elements being positioned to form the boundaries of an electrostatic field having both uniform and nonuniform potential gradients,

(2) a pair of electrode elements in each of said groups being in relatively closer proximity to each other than to the third elect-rode element of each of said groups,

(3) each of said pair of electrode elements being adjacent said input means,

(4) one electrode in each pair being closer to said input means than the second electrode of each pair,

(5) the third electrode of each of the aforesaid groups being closer to said second electrode of each pair than to the first and separated from said second electrode by a distance sufficient to prevent arcing,

(6) said third electrode being mounted for rotation in a direction similar to that of said second electrode,

(7) said third electrodes of each group being further mounted for rotation in close proximity in a direction opposite to each other,

(8) the electrodes in each pair being mounted for rotation in opposite directions;

(c) means connected to each of said pairs of electrode elements to apply a like electrostatic charge thereto, the electrodes of a pair being also electrically connected to each other;

(d) means connected to the third electrode of each group to apply an electrostatic charge opposite to that applied to said pairs of electrodes, said second and third electrodes being so disposed that, upon application of the electrostatic charges thereto, there is produced an electrostatic field of high intensity;

(e) first dofiing means for removing long fibers from 6 between said second and third electrode elements, said first dofling means being mounted therebetween at a distance no closer to said electrode elements than the midpoint of the length of the short fibers to be separated;

(f) means for rotating said electrode elements;

(g) means adjacent said first dofiing means for collecting separated long fibers;

(h) second dofling means for removing short fibers;

and

(i) a chamber for collecting short fibers in proximity to said third electrode elements, said chamber having means connected thereto to place an electrostatic charge thereon similar to that of said third electrode elements.

2. An apparatus according to claim 1 wherein the first dofling means for recovering the long fibers consists of rotating nonconducting fingers which mechanically sweep the region of high field intensity and wherein the means for collecting long fibers adjacent said first dofiing means comprises chambers provided with removable screens, said long fibers being removed from the fingers by air currents and recovered on said removable screens.

3. The apparatus according to claim 2 wherein the doffing means for recovering the short fibers are felt wipers.

4. The apparatus according to claim 1 wherein the potential ranges from about 0.5 to 30 kilovolts per inch of finite distance between the opposing electrodes.

5. A process for separating short fibers from loose masses of mixtures of relatively untangled, individualized long and short textile fibers comprising:

(a) forming an electrostatic field having both uniform and nonuniform potential gradients between a plurality of oppositely charged electrode elements;

(b) introducing said fibers in the area having the lowest potential gradient;

(c) moving said fibers in a direction parallel to the nonuniform potential gradients whereupon the long fibers in the loose mass are attracted to the region of highest potential gradient, the short fibers being relatively unaffected, whereby a portion of said short fibers passes through the electrostatic 'field in the region of lowest potential gradient and a portion adheres to said electrode elements;

((1) mechanically removing the adhering portion of short fibers from the electrode elements and collecting said portion together with the portion passing through the region of lowest potential gradient of the electrostatic field;

(e) separately removing the long fibers from the region of highest potential gradient; and

(f) separately collecting said long fibers.

6. A process according to claim 5 wherein the long fibers are mechanically swept in a motion perpendicular to the lines of force by a sweeping action applied at a distance no closer to the electrode elements than the midpoint of the length of the short fibers.

7. Apparatus for separating short fibers from loose masses of relatively untangled mixtures of individualized long and short textile fibers which comprises:

(a) input means for admitting a loose mass of a relatively untangled mixture of individualized long and short textile fibers into the apparatus;

(b) four parallel, rotatable cylindrical electrode elements symmetrically arranged in two groups of two elements on opposite sides of a center line to form a mirror image of each other, said four elements being positioned to form the boundaries of an electrostatic field having both uniform and nonuniform potential gradients,

(1) a first cylindrical, electrode element on each side of the center line adjacent to the input means and mounted for rotation in a direction parallel with that of the incoming fibers,

(2) a second cylindrical electrode element on each side of the center line forming the opposing electrode situated a finite distance from the surface of the first electrode element, said finite distance being sufliciently great to prevent arcing, said combination of the first element and the opposing second element on each side of the center line defining the sides of the fields of force, said second elements being in close proximity with each other and mounted for rotation in opposite directions;

(c) means connected to each of said first electrode elements to apply a like electrostatic charge thereto;

((1) means connected to each of said second electrode elements to apply an electrostatic charge opposite to that applied to said first electrode elements;

(e) first dotfing means for removing long fibers, said first dofiing means comprising rotatable nonconducting fingers positioned between said first and second electrode elements of each group in a region of high electrostatic field intensity and at a distance from said electrode elements no closer than midpoint of the length of the short fibers;

(f) a first collecting chamber adjacent each of said first dotfing means, said first collecting chambers being provided with removable screens for collecting long fibers removed from between the first andsecond electrode elements;

(g) second doffing means in wiping contact with each electrode element for removing short fibers adhering thereto;

(h) a second collecting chamber adjacent the second electrode elements for collecting short fibers, said second collecting chamber being connected to a source of electrostatic potential of a charge similar to that on the second electrode elements; and

(i) means for driving the rotatable electrode'elements and the rotatable fingers.

8. Apparatus for separating short fibers from loose masses of relatively untangled mixtures of individualized long and short textile fibers which comprises:

(a) input means for admitting a loose mass of a relatively untangled mixture of individualized long and short textile fibers into the apparatus;

(b) an elongated electrically nonconducting wall member extending away from said input means;

(c) three parallel, rotatable, cylindrical electrode elements mounted at successively increasing distances from the input means in such manner that the first two electrode elements rotate in opposite directions :and the second and third electrode elements rotate in the same direction,

(1) said three electrode elements together with the nonconducting wall member defining the boundaries of an electrostatic field having both uniform and nonuniform potential gradients,

(2) the first two electrode elements being in relatively closer proximity to each other than the distance between the second and third electrode element, the distance between the second and third electrode elements being sufficient to prevent arcing;

(d) means connected to said first and second electrode elements to apply a like electrostatic charge thereto;

(e) means connected to the third electrode element to apply an electrostatic charge opposite to that applied to the first and second electrode elements, said second and third electrode elements being so disposed that, upon application of the electrostatic charges thereto, there is produced between them an electrostatic field of high intensity;

(f) first doffing means for removing long fibers from between said second and third electrode elements, said first doffing means being mounted therebetween at a distance no closer to said electrode elements 8 than the midpoint of the length of the short fibers to be separated; (g) a first collecting chamber adjacent said first doffing means, said first collecting chamber being provided with a removable screen for collecting long fibers removed from between the second and third electrode elements;

(h) second dofiing electrode element thereto;

(i) a second collecting chamber adjacent the third electrode element for collecting short fibers, said second collecting chamber being connected to a source of electrostatic potential of a charge similar to that on that on the third electrode element; and

(j) means for driving the electrode elements and the first doffing means.

9. Apparatus for separating short fibers from loose masses of relatively untangled mixtures of individualized long and short textile fibers which comprises:

(a) input means for admitting a loose mass of a relatively untangled mixture of individualized long and short textile fibers into the apparatus;

(b) an elongated electrically nonconducting wall member extending away from said input means;

(c) first and second rotatable cylindrical electrode elements mounted so that the first electrode element is closer to the input means than the second electrode element,

(1) said electrode elements together with the nonconducting wall member defining the boundaries of an electrostatic field having both uniform and and nonuniform potential gradients,

(2) the distance between the electrode elements being sufficient to prevent arcing;

(d) means connected to the first electrode element to apply an electrostatic charge thereto;

(e) means connected to the second electrode element to apply an electrostatic charge thereto opposite to that applied to the first electrode element, said two electrode elements being so disposed that, upon application of the electrostatic charges thereto, there is produced between them an electrostatic field of high intensity;

(f) first dotfing means for removing long fibers from between said two electrode elements, said first doffing means being mounted therebetween at a distance no closer to said electrode elements than the midpoint of the length of the short fibers to be separated;

(g) a first collecting chamber adjacent said first doffing means, said first collecting chamber being provided with a removable screen for collecting long fibers removed from between the electrode elements;

(h) second doffing means in wiping contact with each electrode element for removing short fibers adhering thereto;

(i) a second collecting chamber adjacent the second electrode element for collecting short fibers, said second collecting chamber being connected to a source of electrostatic potential of a charge similar to that on the second electrode element; and

(j) means for driving the electrode elements and the first doffing means.

means in wiping contact with each for removing short fibers adhering References Cited UNITED STATES PATENTS FOREIGN PATENTS 8/ 1955 Great Britain.

FRANK W. LUTTER, Primary Examiner. 

1. APPARATUS FOR SEPARATING SHORT FIBERS FROM LOOSE MASSES OF RELATIVELY UNTANGLED MIXTRURES OF INDIVIDUALIZED LONG AND SHORT TEXTILE FIBERS WHICH COMPRISES: (A) INPUT MEANS FOR ADMITING A LOOSE MASS OF A RELATIVELY UNTANGLED MIXTURE OF INDIVIDUALIZED LONG AND SHORT TEXTILE FIBERS INTO THE APPARATUS; (B) SIX PARALLEL, ROTATABLE CYLINDRICAL ELECTRODE ELEMENTS SYMMETRICALLY ARRANGED IN TWO GROUPS OF THREE ELEMENTS ON OPPOSITE SIDES OF A CENTER LINE TO FORM A MIRROR IMAGE OF EACH OTHER, (1) SAID SIX ELECTRODE ELEMENTS BEING POSITIONED TO FROM THE BOUNDARIES OF AN ELECTROSTATIC FIELD HAVING BOTH UNIFORM AND NONUNIFORM POTENTIAL GRADIENTS, (2) A PAIR OF ELECTRODE ELEMENTS IN EACH OF SAID GROUPS BEING IN RELATIVELY CLOSER PROXIMITY TO EACH OTHER THAN TO THE THIRD ELECTRODE ELEMENT OF EACH OF SAID GROUPS, (3) EACH OF SAID PAIR OF ELECTRODE ELEMENTS BEING ADJACENT SAID INPUT MEANS, (4) ONE ELECTRODE IN EACH PAIR BEING CLOSER TO SAID INPUT MEANS THAN THE SECOND ELECTRODE OF EACH PAIR, (5) THE THIRD ELECTRODE OF EACH OF THE AFORESAID GROUPS BEING CLOSER TO SAID SECOND ELECTRODE OF EACH PAIR THAN TO THE FIRST AND SEPARATE FROM SAID SECOND ELECTRODE BY A DISTANCE SUFFICIENT TO PREVENT ARCING, (6) SAID THIRD ELECTRODE BEING MOUNTED FOR ROTATION IN A DIRECTION SIMILAR TO THAT OF SAID SECOND ELECTRODE, (7) SAID THIRD ELECTRODE OF EACH GROUP GEING FURTHER MOUNTED FOR ROTATION IN CLOSE PROXIMITY IN A DIRECTION OPPOSITE TO EACH OTHER, (8) THE ELECTRODES IN EACH PAIR BEING MOUNTED FOR ROTATION IN OPPOSITE DIRECTIONS; (C) MEANS CONNECTED TO EACH OF SAID PAIRS OF ELECTRODE ELEMENTS TO APPLY A LIKE ELECTROSTATIC CHARGE THERETO, THE ELECTRODES OF A PAIR BEING ALSO ELECTRICALLY CONNECTED TO EACH OTHER; (D) MEANS CONNECTED TO THE THIRD ELECTRODE OF EACH GROUP OF APPLY AN ELECTROSTATIC CHARGE OPPOSITE TO THAT APPLIED TO SAID PAIRS OF ELECTRODES, SAID SECOND AND THIRD ELECTRODES BEING SO DISPOSED THAT, UPON APPLICATION OF THE ELECTROSTATIC CHARGE THERETO, THERE IS PRODUCED AN ELECTROSTATIC FIELD OF HIGH INTENSITY; (E) FIRST DOFFING MEANS FOR REMOFING LONG FIBERS FROM BETWEEN SAID SECOND AND THIRD ELECTRODE ELEMENTS, SAID FIRST DOFFING MEANS BEING MOUNTED THEREBETWEEN AT A DISTANCE NO CLOSER TO SAID ELECTRODE MEANS THAN THE MIDPOINT OF THE LENGTH OF THE SHORT FIBERS TO BE SEPARATED; (F) MEANS FOR ROTATING SAID ELECTRODE ELEMENTS; (G) MEANS ADJACENT SAID FIRST DOFFING MEANS FOR COLLECTING SEPARATED LONG FIBERS; (H) SECOND DOFFING MEANS FOR REMOVING SHORT FIBERS; AND (I) A CHAMBER FOR COLLECTING SHORT FIBERS IN PROXIMITY TO SAID THIRD ELECTRODE ELEMENTS, SAID CHAMBER HAVING MEANS CONNECTED THERETO TO PLACE AN ELECTROSTATIC CHARGE THEREON SIMILAR TO THAT OF SAID THIRD ELECTRODE ELEMENTS. 